JAMB UTME - Chemistry - 2019

Duba Amsa

Tambaya 2 Rahoto

The part of the total energy of a system that accounts for the useful work done in a system is known as

Enthalpy change

None of the above

Gibb's free energy

Entropy

Energy Changes

Duba Amsa

Tambaya 3 Rahoto

An element Z contains 80% of $_{8}^{16}$ Z and 20% of $_{8}^{18}$ Z. Its relative atomic mass is

16.2

17.6

16.0

16.4

Bayanin Amsa

R.A.M of Z = $16 (\frac{80}{100}) + 18 (\frac{20}{100})$
= $12.8 + 3.6$
= 16.4

Karanta bayanin darasi akan Separation Of Mixtures And Purification Of Chemical Substances (JAMB)

Karanta bayanin darasi akan Atomic Structure And Bonding (JAMB)

Separation Of Mixtures And Purification Of Chemical Substances

Duba Amsa

Tambaya 4 Rahoto

Which of the following could not be alkane?

C

_{4}

H

_{10}

C

_{5}

H

_{12}

C

_{7}

H

_{14}

C

_{8}

H

_{18}

Duba Amsa

Tambaya 5 Rahoto

Which of the following conditions will most enhance the spontaneity of a reaction?

Δ

H is negative and greater than T

Δ

S

Δ

H is negative and

Δ

S = 0

Δ

H is positive and less than T

Δ

S

Δ

H is positive and equal to T

Δ

S

Duba Amsa

Tambaya 6 Rahoto

In the reaction between sodium hydroxide and tetraoxosulphate (VI) solutions, what volume of 0.5 molar sodium hydroxide would exactly neutralize 10cm $^{3}$ of 1.25 molar tetraoxosulphate (vi) acid?

25cm

^{3}

10cm

^{3}

20cm

^{3}

50cm

^{3}

Bayanin Amsa

Equation of reaction : 2NaOH + H $_{2}$ SO $_{4}$ → Na $_{2}$ SO $_{4}$ + 2H $_{2}$ O

Concentration of a base, CB = 0.5M

Volume of acid, V $_{A}$ = 10cm $^{3}$

Concentration of an acid, C $_{A}$ = 1.25M

Volume of base, V $_{B}$ = ?

Recall:
$\frac{C_{A} V_{A}}{C_{B} V_{B}} = \frac{n_{A}}{n_{B}}$ ... (1)
N.B: From the equation,
$\frac{n_{A}}{n_{B}} = \frac{1}{2}$

From (1)
$\frac{1.25 \times 10}{0.5 \times V_{B}} = \frac{1}{2}$
$\frac{12.5}{0.5 V_{B}} = \frac{1}{2}$
25 = 0.5V $_{B}$

VB = 50.0 cm $^{3}$

Karanta bayanin darasi akan Stoichiometry And Chemical Reactions (WAEC)

Duba Amsa

Tambaya 7 Rahoto

The following are isoelectronic ions except

Na

^{+}

Mg

^{2 +}

Si

^{2 +}

O

^{2 +}

Bayanin Amsa

Two or more ions are said to be isoelectronic if they have the same electronic structure and the same number of valence electrons.
Na $^{+}$ = 10 electrons = 2, 8
Mg $^{2 +}$ = 10 electrons = 2,8
O $^{2 -}$ = 10 electrons = 2,8
Si $^{2 +}$ = 12 electrons = 2,8,2
$⟹$ Si $^{2 +}$ is not isoelectronic with the rest.

Karanta bayanin darasi akan Acids, Bases And Salts (Nigeria Only) (WAEC)

Karanta bayanin darasi akan Atomic Structure And Bonding (JAMB)

Acids, Bases And Salts (Nigeria Only)

Duba Amsa

Tambaya 8 Rahoto

A certain hydrocarbon on complete combustion at s.t.p produced 89.6dm $^{3}$ of CO $_{2}$ and 54g of water. The hydrocarbon should be

C

_{6}

H

_{6}

C

_{4}

H

_{10}

C

_{5}

H

_{10}

C

_{4}

H

_{6}

Duba Amsa

Tambaya 9 Rahoto

Hydrocarbons which will react with Tollen's reagent conform to the general formula

C

_{n}

H

_{2 n}

C

_{n}

H

_{2 n + 2}

C

_{n}

H

_{2 n - 2}

C

_{n}

H

_{2 n + 1}

OH

Duba Amsa

Tambaya 10 Rahoto

Na $_{2}$ CO $_{3}$ + 2HCl $\to$ 2NaCl + H $_{2}$ O + CO $_{2}$

The indicator most suitable for this reaction should have a pH equal to

5

7

3

9

Acids, Bases And Salts

Duba Amsa

Tambaya 11 Rahoto

In the reaction:

M + N → P

ΔH = +Q kJWhich of the following would increase the concentration of the product?

Adding a suitable catalyst

Increasing the concentration of P

Increasing the temperature

Decreasing the temperature

Duba Amsa

Tambaya 12 Rahoto

The hybridization in the compound $C H_{3} - C H_{2} - C \equiv H$ is

sp

^{3}

and sp

sp

^{2}

sp

^{3}

and sp

^{2}

Bayanin Amsa

The hybridization in a and b is sp $^{3}$ hybridization while in c and d is sp hybridization.

Duba Amsa

Tambaya 13 Rahoto

The two ions responsible for hardness in water are

Ca

^{2 +}

and / or Mg

^{2 +}

K

^{+}

and / or Mg

^{2 +}

Ca

^{2 +}

and / or Li

^{+}

Ca

^{2 +}

and / or Na

^{+}

Solubility

Water

Duba Amsa

Tambaya 14 Rahoto

Which quantum divides shells into orbitals?

Spin

Principal

Azimuthal

Magnetic

Duba Amsa

Tambaya 15 Rahoto

Consider the reaction: A + 2B $_{(g)} ⇌$ 2C + D $_{(g)}$ ( $Δ$ H = +ve)

What will be the effect of decrease in temperature on the reaction?

Rate of backward reaction will increase

The equilibrium constant will shift

Rates of forward and backward reactions are not affected

Rate of forward reaction will increase

Chemical Equilibra

Duba Amsa

Tambaya 16 Rahoto

Which of the following is a physical change?

Exposing white phosphorus to air

Burning kerosene

Dissolving calcium in water

Freezing ice cream

Duba Amsa

Tambaya 17 Rahoto

The reaction $2 H_{2} S + S O_{2} \to 3 S + 2 H_{2} O$ is

not a redox reaction because there is no oxidant in the reaction

not a redox reaction because there is no reductant in the reaction

a redox reaction in which H

_{2}

S is the oxidant and SO

_{2}

is the reductant

a redox reaction in which SO

_{2}

is the oxidant and H

_{2}

S is the reductant

Duba Amsa

Tambaya 18 Rahoto

The combustion of carbon(ii)oxide in oxygen can be represented by equation.

2CO + O $_{2}$ ? 2CO $_{2}$

Calculate the volume of the resulting mixture at the end of the reaction if 50cm $_{3}$ of carbon(ii)oxide was exploded in 100cm $_{3}$ of oxygen

75cm

^{3}

125cm

^{3}

100cm

^{3}

50cm

^{3}

Duba Amsa

Tambaya 19 Rahoto

Which of the following describes the chemical property of acids?

None of the above

Acid + XCO

_{3}

\to

Salt + H

_{2}

O + NH

_{3}

Acid + NaOH

\to

Normal salt + CO

_{2}

Acid + X

_{n}

CO

_{3}

\to

Salt + H

_{2}

O + CO

_{2}

Acids, Bases And Salts

Duba Amsa

Tambaya 20 Rahoto

The molecular shape and bond angle of water are respectively

linear, 180°

bent, 109.5°

tetrahedral, 109.5°

bent, 105°

Duba Amsa

Tambaya 21 Rahoto

Which of the following pairs cannot be represented with a chemical formula?

air and bronze

bronze and sodium chloride

copper and sodium chloride

caustic soda and washing soda

Metals And Their Compounds

Duba Amsa

Tambaya 22 Rahoto

The IUPAC nomenclature of the compound

H $_{3}$ C - CH(CH $_{3}$ ) - CH(CH $_{3}$ ) - CH $_{2}$ - CH $_{3}$

3,4- dimethylhexane

2,3- dimethyl pentane

2- ethyl hexane

2,3- dimethylhexane

Duba Amsa

Tambaya 23 Rahoto

Elements X and Y have electronic configurations 1s $^{2}$ 2s $^{2}$ 2p $^{4}$ and 1s $^{2}$ 2s $^{2}$ 2p $^{6}$ 3s $^{2}$ 3p $^{1}$ respectively. When they combine, the formula of the compound formed is

XY

X

_{2}

Y

_{2}

X

_{3}

X

_{2}

Y

_{3}

Duba Amsa

Tambaya 24 Rahoto

Which of the following statements does not show Rutherford's account of Nuclear Theory? An atom contains a region

which contains protons and neutrons

which is positively charged

which is massive and can cause deflection of a few projectiles

which is very large and in which close to 98% of projectiles pass undeflected

Duba Amsa

Tambaya 25 Rahoto

When ammonia and hydrogen ion bond together to form ammonium ion, the bond formed is called

electrovalent bond

co-ordinate bond

ionic bond

covalent bond

Oxidation And Reduction

Duba Amsa

Tambaya 26 Rahoto

For the general equation of the nature

XP + yQ ⇌ mR + nS, the expression for the equilibrium constant is

k[P]

^{x}

[Q]

^{y}

\frac{m [R] [S]}{x [P] y [Q]}

\frac{[P]^{x} [Q]^{y}}{[R]^{m} [S]^{n}}

\frac{[R]^{m} [S]^{n}}{[P]^{x} [Q]^{y}}

Bayanin Amsa

The expression for the equilibrium constant for the general equation XP + yQ ⇌ mR + nS is: Kc = [R]m[S]n / [P]x[Q]y where Kc is the equilibrium constant, [R] and [S] are the concentrations of the products, and [P] and [Q] are the concentrations of the reactants, all raised to the stoichiometric coefficients (m, n, x, y) in the balanced equation. This equation is known as the equilibrium constant expression and it represents the ratio of the concentrations of the products and reactants at equilibrium for a particular chemical reaction. The equilibrium constant is a measure of how far a reaction proceeds towards completion, with a larger value indicating a greater extent of reaction. The equilibrium constant expression is derived from the law of mass action, which states that the rate of a chemical reaction is proportional to the product of the concentrations of the reactants raised to their stoichiometric coefficients. At equilibrium, the rates of the forward and reverse reactions are equal, and the equilibrium constant expression represents the ratio of the rate constants for these two reactions. Therefore, the correct expression for the equilibrium constant for the general equation XP + yQ ⇌ mR + nS is Kc = [R]m[S]n / [P]x[Q]y.

Karanta bayanin darasi akan Chemical Kinetics And Equilibrium Systems (Ghana Only) (WAEC)

Karanta bayanin darasi akan Chemical Equilibra (JAMB)

Chemical Kinetics And Equilibrium Systems (Ghana Only)

Chemical Equilibra

Duba Amsa

Tambaya 27 Rahoto

Which of the following reactions is an oxidation process?

2H

^{+}

+ 2e

^{-}

\to

H

_{2}

2O

^{2 -}

+ 4e

^{-}

\to

O

_{2}

OCl

^{-}

+ H

_{2}

O + 2e

^{-}

\to

2OH

^{-}

+ Cl

^{-}

Cl + e

^{-}

\to

Cl

^{-}

Oxidation And Reduction

Duba Amsa

Tambaya 28 Rahoto

Elements in the periodic table are arranged in the order of their

atomic numbers

metallic character

mass number

relative atomic mass

Duba Amsa

Tambaya 29 Rahoto

The oxidation state(s) of nitrogen in ammonium nitrite is/are

-3, +3

+5

-3, +5

-3

Bayanin Amsa

Ammonium nitrite = NH $_{4}$ NO $_{2}$
NH $_{4}^{+}$ : Let the oxidation number of Nitrogen = x
x + 4 = 1 $⟹$ x = 1 - 4
x = -3
NO $_{2}^{-}$ : x - 4 = -1
x = -1 + 4 $⟹$ x = +3.
The oxidation numbers for Nitrogen in Ammonium Nitrite = -3, +3.

Karanta bayanin darasi akan Oxidation And Reduction (JAMB)

Oxidation And Reduction

Duba Amsa

Tambaya 30 Rahoto

What volume of 0.100M sodium trioxonitrate (V) solution contains 5g of solute.

[Na = 23, N = 14, O = 16]

1.7 litres

0.420 litres

0.588 litres

2.35 litres

Duba Amsa

Tambaya 31 Rahoto

The shapes of water, ammonia, carbon (iv) oxide and methane are respectively

linear, tetrahedral, angular and pyramidal

angular, pyramidal, linear and tetrahedral

pyramidal, linear, tetrahedral and angular

tetrahedral, angular, pyramidal and linear

Duba Amsa

Tambaya 32 Rahoto

At 27°C, 58.5g of sodium chloride is present in 250cm $^{3}$ of a solution. The solubility of sodium chloride at this temperature is?

(molar mass of sodium chloride = 111.0gmol $^{- 1}$ )

2.0 moldm

^{- 3}

0.25 moldm

^{- 3}

1.0 moldm

^{- 3}

0.5 moldm

^{- 3}

Bayanin Amsa

Given the Mass of the salt = 58.5g
Volume = 250 cm $^{3}$ = 0.25 dm $^{3}$
Mass concentration = $\frac{M a s s}{V o l u m e}$
= $\frac{58.5}{0.25}$ = 234 gdm $^{- 3}$
Solubility (in moldm $^{- 3}$ = $\frac{234}{111}$
= 2.11 moldm $^{- 3}$
$≊$ 2.0 moldm $^{- 3}$

Karanta bayanin darasi akan Solubility Of Substances (Ghana Only) (WAEC)

Solubility Of Substances (Ghana Only)

Duba Amsa

Tambaya 33 Rahoto

The emission of two successive beta particles from the nucleus $_{15}^{32} P$ will produce

_{14}^{30}

Si

_{13}^{32}

Al

_{17}^{32}

Cl

_{16}^{32}

S

Bayanin Amsa

Explanation:

_{15}^{32}

P

\to

2

_{- 1}^{0}

e +

_{b}^{a}

X
32 = 2(0) + a
a = 32
15 = 2(-1) + b
b = 15 + 2
b = 17

∴

_{b}^{a}

X =

_{17}^{32}

Cl

Karanta bayanin darasi akan Structure Of The Atom (WAEC)

Structure Of The Atom

Duba Amsa

Tambaya 34 Rahoto

Which of the following sets of operation will completely separate a mixture of sodium chloride, sand and iodine?

addition of water, filtration, evaporation to dryness and sublimation

filtration, evaporation to dryness, addition of water and sublimation

sublimation, filtration, evaporation and addition of water

sublimation, addition of water, filtration and evaporation to dryness

Separation Of Mixtures And Purification Of Chemical Substances

Duba Amsa

Tambaya 35 Rahoto

If acidified Potassium Dichromate(VI) (K $_{2}$ Cr $_{2}$ O $_{7}$ ) acts as oxidizing agent, color changes from

yellow to green

orange to green

yellow to red

orange to red

Oxidation And Reduction

Duba Amsa

Tambaya 36 Rahoto

Consider the reaction

A $_{(s)}$ + 2B $_{(g)}$ → 2C $_{(a q)}$ + D $_{(g)}$

What will be the effect of a decrease in pressure on the reaction?

the equilibrium will shift

rate of forward reaction will increase

rate of backward reaction will increase

rates of forward and backward reaction are not affected

Bayanin Amsa

Given: The equation below

A $_{(s)}$ + 2B $_{(g)}$ → 2C $_{(a q)}$ + D $_{(g)}$

Since we have a higher number of moles of gaseous species on the LHS, i.e 2, a decrease in pressure will favor the forward reaction.

Karanta bayanin darasi akan Kinetic Theory Of Matter And Gas Laws (JAMB)

Karanta bayanin darasi akan Chemical Kinetics And Equilibrium Systems (Ghana Only) (WAEC)

Karanta bayanin darasi akan Periodic Chemistry (Ghana Only) (WAEC)

Chemical Kinetics And Equilibrium Systems (Ghana Only)

Periodic Chemistry (Ghana Only)

Duba Amsa

Tambaya 37 Rahoto

How many alkoxyalkanes can be obtained from the molecular formula C $_{4}$ H $_{10}$ O?

4

2

1

3

Acids, Bases And Salts (Nigeria Only)

Chemical Equilibra

Duba Amsa

Tambaya 38 Rahoto

SO $_{3}$ is not directly dissolved in water in the industrial preparation of H $_{2}$ SO $_{4}$ by the contact process because

SO

_{3}

is an acidic gas

Acid is usually added to water and not water to acid

The reaction between SO

_{3}

and water is violently exothermic

SO

_{3}

does not dissolve readily in water

Acids, Bases And Salts

Duba Amsa

Tambaya 39 Rahoto

The IUPAC name for CH $_{3}$ CH $_{2}$ COOCH $_{2}$ CH $_{3}$ is

methylpropanoate

ethylethanoate

ethylpropanoate

methylethanoate

Duba Amsa

Tambaya 40 Rahoto

By what amount must the temperature of 200cm $^{3}$ of Nitrogen at 27°C be increased to double the pressure if the final volume is 150cm $^{3}$ (Assume ideality)

150°C

177°C

75°C

120°C

Bayanin Amsa

Using the ideal gas law and equation:
$\frac{P_{1} V_{1}}{T_{1}} = \frac{P_{2} V_{2}}{T_{2}}$
$\frac{P_{1} \times 200 {cm}^{3}}{300 K} = \frac{2 P \times 150 {cm}^{3}}{T_{2}}$
Cross multiply:
$T_{2} = \frac{300 \times 150 \times 2 P}{200 \times P}$
$= 450 K$ or $177^{\circ} C$
Don't forget to convert to $^{\circ} C$

Karanta bayanin darasi akan Kinetic Theory Of Matter And Gas Laws (JAMB)